Pulley assembly for high-speed continuously variable transmission

ABSTRACT

A pulley assembly for a high-speed continuously variable transmission includes a drive pulley, a shaft sleeve, a movable pulley, rollers, and a back pressure disc. The movable pulley has a shaft portion fitted on the shaft sleeve. The movable pulley has a disc chamber radially formed with multiple pairs of retaining wall pieces. A receiving room is defined between each pair of the retaining wall pieces. The bottom of the receiving room has an inclined push surface. The rollers are received in the receiving rooms. The back pressure disc includes a disc body having a complete inner conical surface. The back pressure disc is subject to the shaft sleeve and unable to be axially displaced along an output shaft. The peripheral edge of the disc body is embedded into the disc chamber of the movable pulley. The inner conical surface is pressed against the rollers.

FIELD OF THE INVENTION

The present invention relates to a pulley assembly, and moreparticularly to a pulley assembly for a flexible axial movement of amovable pulley on a shaft sleeve to effectively improve the smoothnessand efficiency of the speed-change operation for a continuously variabletransmission.

BACKGROUND OF THE INVENTION

An automatic variable transmission or continuously variable transmissionfor vehicles (such as motorcycles) is commercially available in a weightroller structure of automatic variable transmission device whichcomprises a movable transmission disc formed with a plurality of weightroller rooms. Each weight roller room is provided with a weight roller.Each weight roller is subject to a holding disc. Through the centrifugaloutward displacement of the weight rollers, the movable transmissiondisc is forced to move toward a drive disc along a central shaft so thatthe distance between the movable transmission disc and the drive disc isreduced and changed and a V-shaped transmission belt between the movabletransmission disc and the drive disc can change its transmissionposition with the speed of the movable transmission disc to achieve theeffect of an automatic speed change.

For the aforesaid conventional automatic variable transmission orcontinuously variable transmission to achieve the object of a steplessautomatic speed change, as shown in FIGS. 1, 2, 3 and 4, the center of amovable transmission disc 1 is radially formed with a plurality ofweight roller rooms 11 each having a push surface 110 inclined inward.Each weight roller room 11 is provided with a weight roller 3. Eachweight roller 3 on the push surface 110 is subject to an inclined discbody portion 20 of a holding disc 2. As shown in FIG. 5 and FIG. 6, whenthe drive disc 5 is driven by a central shaft 6, the movabletransmission disc 1 is forced to move toward the drive disc 5 along thecentral shaft 6 through the centrifugal outward displacement of theweight rollers 3, so that the distance between the movable transmissiondisc 1 and the drive disc 5 is reduced and changed, and a V-shapedtransmission belt 4 between the movable transmission disc 1 and thedrive disc 5 can change its transmission position from inside to outsidewith the rotational speed of the movable transmission disc 1 to changethe transmission speed ratio of the V-shaped transmission belt 4. Asshown in FIG. 3 and FIG. 6, through the centrifugal outward displacementof the weight rollers 3, the movable transmission disc 1 is forced tomove axially to change the distance between the movable transmissiondisc 1 and the drive disc 5 and further to change the transmissionposition of the V-shaped transmission belt 4. When the center shaft 6drives the drive disc 5 and the holding disc 2, in order to prevent theweight rollers 3 from being displaced from the inclined disc bodyportion 20 of the holding disc 2, as shown in FIG. 1, FIG. 2 and FIG. 4,the movable transmission disc 1 is provided with a plurality of guideposts 12 extending outward and each disposed between every two of theweight roller rooms 11. In addition, the inclined disc body portion 20of the holding disc 2 is formed with a plurality of recesses 200. Therecesses 200 are formed with guide notches 21 corresponding to the guideposts 12. Through the guide posts 12 engaged in the guide notches 21respectively, the holding disc 2 is synchronously rotated with themovable transmission disc 1, thereby preventing the press surface thatthe inclined disc body portion 20 of the holding disc 2 acts on theweight rollers 3 from being deviated. The holding disc 2 is not allowedto be axially displaced because the notches 21 are mated with the guideposts 12 of the movable transmission disc 1 to form a synchronous link.As a result, during the axial displacement of the movable transmissiondisc 1, a strong frictional resistance is formed between the guide posts12 and the guide notches 21 to lower the flexibility of changing thedistance between the movable transmission disc 1 and the drive disc 5.This affects the smoothness of the V-shaped transmission belt 4 tochange its transmission position or affects the efficiency of a speedchange. Accordingly, the inventor of the present invention has devotedhimself based on his many years of practical experiences to solve theseproblems.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a pulleyassembly for a high-speed continuously variable transmission. The pulleyassembly comprises a drive pulley, a shaft sleeve, a movable pulley, aplurality of rollers, and a back pressure disc. The drive pulley isconnected with an output shaft and has a first belt acting disc surfaceinclined outward. The shaft sleeve is mounted on the output shaft. Themovable pulley has a shaft portion fitted on the shaft sleeve, allowingthe movable pulley to move axially along the shaft sleeve. One end ofthe movable pulley is formed with a second belt acting disc surfaceinclined outward opposite the first belt acting disc surface of thedrive pulley. Another end of the movable pulley is formed with a discrim around an outer periphery of the shaft portion to form a discchamber. The disc chamber is radially formed with a plurality of pairsof retaining wall pieces extending in the direction of the disc rim withthe shaft portion as a center thereof. A notch is formed between eachpair of the retaining wall pieces and the disc rim. A receiving room isdefined between each pair of the retaining wall pieces. A bottom of thereceiving room, from the shaft portion to the disc rim, has an inclinedpush surface from deep to shallow. The rollers are received in thereceiving rooms of the pairs of retaining wall pieces of the movablepulley, respectively. The back pressure disc has a disc body in the formof an Asian conical hat. The disc body has a complete inner conicalsurface and a coupling hole at an upper end thereof. The output shaft isinserted through the coupling hole. The back pressure disc is subject tothe shaft sleeve and unable to be axially displaced along the outputshaft. A peripheral edge of the disc body is embedded into the discchamber of the movable pulley over the notch. The inner conical surfaceis pressed against the rollers. When the output shaft drives the drivepulley, the rollers are each displaced along the included push surfaceat the bottom of the receiving room of the movable pulley. The rollers,subject to the limitation of the axial displacement of the inner conicalsurface of the back pressure disc, force the movable pulley to move inthe direction of the drive pulley, that is, the distance between thesecond belt acting disc surface of the movable pulley and the first beltacting disc surface of the drive pulley is reduced so that thetriangular drive belt interposed between the first belt acting discsurface and the second belt acting disc surface changes its driveposition. The movable pulley is axially moved back and forth on theshaft sleeve in response to the speed of the drive pulley. The backpressure disc does not directly interfere with the movable pulley sothat the drive position of the triangular drive belt interposed betweenthe first belt acting disc surface and the second belt acting discsurface is changed to achieve a flexible axial movement of the movablepulley on the shaft sleeve and to effectively improve the smoothness andefficiency of the speed-change operation for the continuously variabletransmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a conventional pulley assembly for acontinuously variable transmission;

FIG. 2 is a planar view of the conventional pulley assembly of FIG. 1;

FIG. 3 is a sectional view taken along line A-A of FIG. 2;

FIG. 4 is a sectional view taken along line B-B of FIG. 2;

FIG. 5 is a schematic view showing the centrifugal displacement of theweight rollers of the conventional pulley assembly of FIG. 1;

FIG. 6 is a sectional view taken along line C-C of FIG. 5;

FIG. 7 is a sectional view taken along line D-D of FIG. 5;

FIG. 8 is an exploded view in accordance with a first embodiment of thepresent invention;

FIG. 9 is a planar view in accordance with the first embodiment of thepresent invention;

FIG. 10 is a sectional view taken along line E-E of FIG. 9;

FIG. 11 is a sectional view taken along line F-F of FIG. 9;

FIG. 12 is a planar view in accordance with the first embodiment of thepresent invention, showing that the rollers are centrifugally displaced;

FIG. 13 is a sectional view taken along line G-G of FIG. 12;

FIG. 14 is a sectional view taken along line H-H of FIG. 12;

FIG. 15 is an exploded view in accordance with a second embodiment ofthe present invention;

FIG. 16 is a sectional view in accordance with the second embodiment ofthe present invention; and

FIG. 17 is a sectional view in accordance with the second embodiment ofthe present invention, showing that the rollers are centrifugallydisplaced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings.

A pulley assembly for a high-speed continuously variable transmission,as shown in FIGS. 8-11, comprises a drive pulley 30, a shaft sleeve 40,a movable pulley 50, a plurality of rollers 60, and a back pressure disc70. The drive pulley 30 is connected with an output shaft 80, and has afirst belt acting disc surface 31 inclined outward. The shaft sleeve 40is mounted on the output shaft 80. The movable pulley 50 has a shaftportion 51 fitted on the shaft sleeve 40, allowing the movable pulley 50to move axially along the shaft sleeve 40. One end of the movable pulley50 is formed with a second belt acting disc surface 52 inclined outwardopposite the first belt acting disc surface 31 of the drive pulley 30.Another end of the movable pulley 50 is formed with a disc rim around anouter periphery of the shaft portion 51 to form a disc chamber 54. Thedisc chamber 54 is radially formed with a plurality of pairs ofretaining wall pieces 55 extending in the direction of the disc rim 53with the shaft portion 51 as a center thereof. A notch 56 is formedbetween each pair of the retaining wall pieces 55 and the disc rim 53. Areceiving room 57 is defined between each pair of the retaining wallpieces 55. The bottom of the receiving room 57, from the shaft portion51 to the disc rim 53, has an inclined push surface 58 from deep toshallow. The rollers 60 are received in the receiving rooms 57 of thepairs of retaining wall pieces 55 of the movable pulley 50,respectively. The back pressure disc 70 has a disc body 71 in the formof an Asian conical hat. The disc body 71 has a complete inner conicalsurface 72 and a coupling hole 73 at an upper end thereof. The outputshaft 80 is inserted through the coupling hole 73. In cooperation withthe limitation or stop of the shaft sleeve 40, the back pressure disc 70can't be axially displaced along the output shaft 80. The peripheraledge of the disc body 71 is embedded into the disc chamber 54 of themovable pulley 50 over the notch 56, without any blocking. The innerconical surface 72 is pressed against a surface of each roller 60. Asshown in FIG. 12, FIG. 13 and FIG. 14, when the output shaft 80 drivesthe drive pulley 30, the rollers 60 are each displaced along theincluded push surface 58 at the bottom of the receiving room 57 of themovable pulley 50. The rollers 60, subject to the limitation of theaxial displacement of the integral inner conical surface 72 of the backpressure disc 70, force the movable pulley 50 to move in the directionof the drive pulley 30, that is, the distance between the second beltacting disc surface 52 of the movable pulley 50 and the first beltacting disc surface 31 of the drive pulley 30 is reduced so that thetriangular drive belt 90 interposed between the first belt acting discsurface 31 and the second belt acting disc surface 52 changes its driveposition, generating an automatic and stepless speed change of thetransmission speed ratio. As shown in FIGS. 10, 11, 13, and 14, themovable pulley 50 is axially moved back and forth on the shaft sleeve 40in response to the speed of the drive pulley 30. The back pressure disc70 does not directly interfere with the movable pulley 50 so that thedrive position of the triangular drive belt 90 interposed between thefirst belt acting disc surface 31 and the second belt acting discsurface 52 is changed to achieve a flexible axial movement of themovable pulley 50 on the shaft sleeve 40 and to effectively improve thesmoothness and efficiency of the speed-change operation for thecontinuously variable transmission.

According to the above-described embodiment, as shown in FIGS. 8, 9 and10, the roller 60 may be a circular roller, or it may be a polygonalroller as shown in FIGS. 15 and 16. Please note that the polygonalroller can refer to the teaching disclosed in Taiwan Patent No. I308122titled “weight roller for automatic variable transmission device” orTaiwan Utility Model No. M425094 titled “anti-roll weight rollerstructure for automatic variable transmission”. The inner conicalsurface 72 of the back pressure disc 70 is pressed against an inclinedsurface 61A of each polygonal roller 60A. As shown in FIG. 16 and FIG.17, when the output shaft 80 drives the drive pulley 30, a slide curvedsurface 62A of each polygonal roller 60A is displaced along the includedpush surface 58 at the bottom of the receiving room 57 of the movablepulley 50. The polygonal rollers 60, subject to the limitation of theaxial displacement of the integral inner conical surface 72 of the backpressure disc 70, force the movable pulley 50 to move in the directionof the drive pulley 30, that is, the distance between the second beltacting disc surface 52 of the movable pulley 50 and the first beltacting disc surface 31 of the drive pulley 30 is reduced to generate anautomatic and stepless speed change of the transmission speed ratio.Similarly, the back pressure disc 70 does not directly interfere withthe movable pulley 50 to achieve a flexible axial movement of themovable pulley 50 on the shaft sleeve 40. Through a speed-change ratetest on a motorcycle, the results are shown in Table 1 and Table 2.(Note: The data of Table 1 and Table 2 are quoted from the test reportof Appendix I.

TABLE 1 the record of the required time for acceleration at thepredetermined speed record at the predetermined speed, the timedisplayed by the timer (minute/second) speed the pulley assembly theconventional Speed per hour of the present pulley (Kmh) inventionassembly 30 01:39 01:50 40 01:41 01:52 50 01:42 01:55 60 01:44 01:58 7001:48 02:02 80 01:52 02:06 90 02:04 02:19

TABLE 2 the required time for acceleration and comparison the requiredtime for acceleration acceleration at the at the predetermined sectionpredetermined section (second) (speed rate) comparison between thepulley assembly speed the pulley the of the present per hour assembly ofthe conventional invention and (Kmh) present pulley the conventionalsection invention assembly pulley assembly 30-40 2 2 the same 30-50 3 52 seconds faster 30-60 5 8 3 seconds faster 30-70 9 12 3 seconds faster30-80 13 16 3 seconds faster 30-90 25 29 4 seconds faster

The data of the test results show that the required time for the pulleyassembly of the present invention to be accelerated from 30 km per hourto 90 km per hour is about 4 seconds faster than that of a conventionalpulley assembly, which proves that the pulley assembly of the presentinvention can effectively improve the smoothness of the speed-changeoperation and the reaction rate of the continuously variabletransmission. In addition, as shown in the test report of the AppendixI, it is confirmed that the pulley assembly of the present inventionalso has the benefits of saving fuel and reducing the wear of therollers.

Although particular embodiments of the present invention have beendescribed in detail for purposes of illustration, various modificationsand enhancements may be made without departing from the spirit and scopeof the present invention. Accordingly, the present invention is not tobe limited except as by the appended claims.

What is claimed is:
 1. A pulley assembly for a high-speed continuouslyvariable transmission, comprising a drive pulley, a shaft sleeve, amovable pulley, a plurality of rollers, and a back pressure disc; thedrive pulley being connected with an output shaft and having a firstbelt acting disc surface inclined outward; the shaft sleeve beingmounted on the output shaft, the movable pulley having a shaft portionfitted on the shaft sleeve, allowing the movable pulley to move axiallyalong the shaft sleeve, one end of the movable pulley being formed witha second belt acting disc surface inclined outward opposite the firstbelt acting disc surface of the drive pulley, another end of the movablepulley being formed with a disc rim around an outer periphery of theshaft portion to form a disc chamber, the disc chamber being radiallyformed with a plurality of pairs of retaining wall pieces extending inthe direction of the disc rim with the shaft portion as a centerthereof, a notch being formed between each pair of the retaining wallpieces and the disc rim, a receiving room being defined between eachpair of the retaining wall pieces, a bottom of the receiving room, fromthe shaft portion to the disc rim, having an inclined push surface fromdeep to shallow; the rollers being received in the receiving rooms ofthe pairs of retaining wall pieces of the movable pulley respectively;the back pressure disc having a disc body in the form of an Asianconical hat, the disc body having a complete inner conical surface and acoupling hole at an upper end thereof, the output shaft being insertedthrough the coupling hole, the back pressure disc being in cooperationwith a limitation of the shaft sleeve and unable to be axially displacedalong the output shaft, a peripheral edge of the disc body beingembedded into the disc chamber of the movable pulley over the notch, andthe rollers are installed in the receiving room, and are between innerconical surface and inclined push surface, and the rollers are pressedagainst the inner conical surface.
 2. The pulley assembly for ahigh-speed continuously variable transmission as claimed in claim 1,wherein the rollers are circular rollers.
 3. The pulley assembly for ahigh-speed continuously variable transmission as claimed in claim 1,wherein the rollers are polygonal rollers.